1270.0.55.004 - Australian Statistical Geography Standard (ASGS): Volume 4 - Significant Urban Areas, Urban Centres and Localities, Section of State, July 2016  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 09/10/2017   
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UNDERSTANDING UCL CHANGES

Urban areas and their populations are dynamic; they can grow, absorb nearby centres or decline. Consequently the Urban Centres and Localities (UCLs) also need to change to enable them to continue to provide an effective statistical representation of these urban areas.

If the populations of small urban areas decline below 200 the Localities that represent these can be removed from the UCL classification. This 200 population limit is set to enable users to access cross classified Census data for these areas without the resulting counts becoming too small for use. There are rules around when the UCLs are removed from the classification and this is explained in more detail in the ‘Design of Urban Centres and Localities’ Chapter.

Some examples of the way UCLs can change are described below.


BOUNDARY CHANGES

The most common change that occurs to a UCL is that it grows in population which typically results in new housing or other infrastructure. UCL boundaries change to include this new growth. Figure 1 shows an example of this for the Urban Centre of 'Cambooya'.


Figure 1. UCL boundary of 'Cambooya' changes to reflect growth in urban areas

On the left: 2011 imagery with an overlay of the 2011 UCL boundary for Cambooya. On the right: 2016 imagery with an overlay of 2016 UCL boundary for Cambooya. The imagery shows growth of the town and the 2016 UCL boundary has changed to accommodate that.
Background image © 2017 DigitalGlobe

When small settlements grow in population they can become new Urban Centres or Localities.

In a small number of situations this growth and even existing urban development can occur in ways that the Statistical Area Level 1 (SA1) boundary does not closely define for a range of reasons. This can result in small areas of urban settlement being left out of the UCL or parts of non-urban land being included in the UCL.

There are four cases where significant amounts of non-urban land have been included in UCLs to ensure that the urban population is also included. This means these UCLs are now much larger in area than their actual urban extent. Users are advised to use the adjusted area for these UCLs; this is supplied in the ‘UCL_association_2011_2016.csv file’ included in the Downloads tab. The adjusted area has been calculated by approximating the urban extent with 2016 Mesh Blocks.

These UCLs are:

    · 313003 Dalby
    · 321063 Jandowae (L)
    · 322013 Bell (L)
    · 522020 Djarindjin - Lombadina (L)


AMALGAMATIONS

When large Urban Centres (over 20,000 people) grow they can expand in area to become adjacent to other smaller, nearby Urban Centres. When this occurs the two Urban Centres are amalgamated to become a single Urban Centre. Figure 2 shows an example of this for the Urban Centres of 'Heddon Greta' and 'Kurri Kurri - Weston'.


Figure 2. The Urban Centres of 'Heddon Greta' and 'Kurri Kurri - Weston' are amalgamated due to growth.

On left: 2011 imagery with an overlay of the 2011 UCL boundaries of Heddon Greta and Kurri Kurri – Weston. On right: 2016 imagery with an overlay of the 2016 UCL boundary for Kurri Kurri. Showing the 2011 UCLs being joined together to accommodate growth.
Background image © 2017 DigitalGlobe

In a very small number of cases the opposite can occur and Urban Centres can be de-amalgamated. This can occur as a result of changes to SA1 boundaries which allow the Urban Centres to be defined more accurately. The most significant example of where this has occurred in 2016 is the de-amalgamation of Victor Harbor – Goolwa in South Australia.


UNDERSTANDING CHANGES

This publication includes the ‘UCL_association_2011_2016.csv file’ which is located in the Downloads tab. This associates 2011 UCLs with an equivalent 2016 UCL to help users understand changes and make statistical comparisons between UCLs over multiple Censuses. This table includes information on the area of the UCLs as well as the following types of changes:
    · Amalgamated – When UCLs have been merged together to form one UCL.
    · De-amalgamated – When UCLs have been split to create several UCLs.
    · Name Change – When an UCL has changed name. This includes the addition or removal of the (L) at the end of a name to symbolise if a UCL is a Locality.
    · New – When an UCL is new for 2016.
    · Removed – When an UCL no longer meets the criteria and is removed from the UCL structure.

ABS Maps is an online mapping tool that allows users to visualise the boundaries and understand differences between different Australian Statistical Geography Standard (ASGS) boundaries, for example the 2011 and 2016 UCLs. This can be used in conjunction with the ‘association file’ to understand the UCL boundaries and any changes that have occurred.